1. Field of the Invention
The present invention relates to a position display system of a mobile terminal, a center station therefor, and a mobile terminal thereof. Particularly, the present invention relates to a position display apparatus of a mobile terminal employing a small zone communication system, a system therefor, and a mobile terminal thereof.
2. Description of the Background Art
A method of detecting the position of a mobile of interest to the present invention is disclosed in Japanese Patent Publication No. 6-93650, for example. According to the present publication, waves from a plurality of repeaters are received at respective mobiles in a mobile communication system for carrying out communication between a repeater and a mobile via a wave. By using a coverage contour of a reception electric field level from each repeater obtained in advance, the range in which a mobile can be located corresponding to each reception level is obtained to detect the current position of a mobile from the overlap of each range.
However, it is difficult to draw the coverage contour in the frequency range used for a general mobile wireless telephone system and, therefore, it is not practical. The reason is that when an intensity of the electric field is to be measured, the fixed value is seldom obtained due to the fact that the electric field value changes depending on the time elapsed and holding attitude or holding direction of the detector owing to a multipath or fading caused by a geography which is affected by building, rows and moving vehicles. As a result, the detected values constantly vary within the range of some dB to some ten dB (microvolts). Therefore, such a system can be applicable only to locate rough position of vehicles moving high speed. However, such a system cannot be applied to the system wherein the location of a man or a vehicle is detected with a precision of some 10 meters.
There are various conventional methods to detect the position of a mobile vehicle or object. Means generally used for detecting the position on the ground and in the streets includes MCA (Multi-Channel Access), AVM (Automatic Vehicle Monitoring System), and GPS (Global Positioning System). Each will be described hereinafter.
(1) MCA
Today, a great number of vehicles for various delivery and transportation such as those of a delivery service company are seen all over the streets. When the dispatch center of a delivery service company wants to inform delivery or reception of an object to one of the delivery vehicles running in town upon receiving a call from a customer, it is common to send the instruction to the vehicle located closest to that customer from the standpoint of time and efficiency. In general, most of the delivery vehicles have a wireless such as of a MCA mounted. Conventionally, the dispatch center contacts the delivery vehicle considered to be running closest to that client by wireless. If the contacted vehicle is actually located near that client, a relevant instruction is provided to that vehicle. If the vehicle is located far away in contrary to the dispatch center""s expectation, other vehicles are contacted sequentially until an appropriately located vehicle is identified. It was common to carry out such confirmation procedures.
(2) AVM
AVM is a practical system that can grasp the current position and state of activity of a running vehicle. This system includes a fixed station (operation control center), a repeater (user operation center), a sign post, and a mobile station. This system is already employed to dispatch taxis and the like efficiently.
(3) GPS
This system is generally employed to identify the position of a mobile vehicle. It is already commercially available as a navigation system for vehicles.
The above-described systems are known as conventional methods for detecting the position of mobile vehicles and objects.
A problem encountered in a MCA will be set forth in the following. If the driver of a vehicle also has to handle the delivery (simply referred to as xe2x80x9cdriverxe2x80x9d hereinafter), the driver must leave the vehicle near the customer""s destination to deliver or receive an item to or from the customer in an apartment or a building of an enterprise. Since the driver is remote from the vehicle during the door delivery or reception, there is a possibility that an inquiry of the position of the vehicle from a wireless of the dispatch center is not responded.
The dispatch center may not easily catch a delivery vehicle near the client even though the client has urgent needs. There was a problem that a complaint was filed of delayed service from customers.
Furthermore, the dispatch center must take the trouble to contact the driver of the mobile vehicle to have the driver""s current location described orally in this MCA method. The driver must be frequently contacted through a wireless to accurately grasp the current position of the vehicle. This is not only tedious, but also places a considerable burden on the driver. In practice, the center side will contact a vehicle arbitrarily by a wireless to reach an appropriate vehicle after repeating contact to several vehicles. There was a problem that confirmation of the position information is troublesome.
In the AVM, a sign post provides the position information. However, such sign posts are installed only in the coverage area of the service vehicle. Naturally, there is a limit in using this system over a wide area range. There is also a problem that the sign post zone is so large that specification of the position of a mobile station becomes too rough to result in low precision of the position. There is also a limit in reducing the size and weight of the mobile station since the output power of the transmitter is 1 W. There is also a problem that the position information of a mobile station must be transmitted to the center station through a taxi wireless and the like, which is rather tedious. Furthermore, extension of the sign posts causes increase in the facility cost.
As to the GPS system, the mobile vehicle per se can confirm its own position. However, additional communication means is required to transmit the position information to the center side. Reduction in size, weight, and cost as a terminal system cannot be achieved.
There are also position confirmation devices that emits a weak wave and that can be carried by children, the aged, and handicapped individuals. However, the coverage area is extremely limited with such a weak wave that is allowed according to the current Wireless Telegraphy Act. Such position confirmation devices are not practical.
In view of the foregoing, an object of the present invention is to provide a position display system of a mobile terminal that can have its position detected at a low cost and with high accuracy.
Another object of the present invention is to provide a mobile terminal that allows position detection at a low cost and at high accuracy.
A further object of the present invention is to provide a center apparatus that is employed in a position detection system of a mobile terminal at a low cost and at high accuracy.
Still another object of the present invention is to provide a system that allows automatic transmission of position information of a mobile terminal carried by a driver and the like to a center apparatus even when the driver is remote from a vehicle.
A still further object of the present invention is to automatically provide the position of a mobile terminal carried by an individual to a center side apparatus without manual operation.
Yet a further object of the present invention is to provide a positioning system that can easily determine a propagation pattern of a wave.
A position display system of a mobile terminal according to an aspect of the present invention employs a small zone communication system. A repeater is provided in respective regions of a plurality of small zones. The position display system of a mobile terminal includes a mobile terminal carrying out communication with a repeater, a center control station for processing communication data with a plurality of repeaters, and a center station connected to the center control station and that can access communication data within the center control station. The center station includes a detection unit for detecting the position of a mobile terminal according to communication data.
Since a mobile terminal communicates with a repeater provided in each of a plurality of small zones so that the center station can access the center control station that processes the communication data to detect the position of the mobile terminal according to the communication data, the center station can easily identify which of the plurality of small zones the mobile terminal is located in.
Preferably, the small zone communication system is a PHS system (Personal Handyphone System). A small zone communication system does not have to be newly developed since an existing PHS system is to be employed.
Preferably, the center control station includes a database for identifying the plurality of small zones. The name of the repeater of the communication destination is stored in the database during communication between a mobile terminal and a repeater. The position detector detects the position of the mobile terminal according to the name of the repeater of the communication destination stored in the database.
Since the database of the center control station is used to detect the position of a mobile terminal, the repeater with which the mobile terminal is communicating can easily be identified.
In the position display system, the mobile terminal preferably includes a wireless communication unit for carrying out wireless communication with the center station. The mobile terminal enters a signal identifying the repeater during communication therewith. The mobile terminal position detector detects the position of the mobile terminal according to the signal from the mobile terminal designating a repeater.
The mobile terminal transmits the signal input during communication with a repeater that designates that repeater to the center station by wireless communication. The center station detects the position of the mobile terminal according to the signal indicating the repeater. Thus, position of a mobile terminal can easily be detected without using the database of the PHS system.
Further preferably, the mobile terminal includes a monitor for monitoring the intensity of an electric field for the plurality of repeaters, and a transmitter to send the electric field intensity of a repeater monitored by the monitor to the center station. The position detector identifies the position of the mobile terminal according to the transmitted electric field intensity of a plurality of repeaters.
Since the mobile terminal monitors the intensity of an electric field for a plurality of repeaters so that the position of the mobile terminal can be identified according to the electric field intensity from the plurality of repeaters, data of the center control station does not have to be used.
According to another aspect of the present invention, the mobile terminal of the first aspect includes an antenna for communication with a base unit, a unit for detecting an identification number that designates a repeater of the communication destination, and an output unit for providing the detected identification number to the center station.
Since the mobile terminal includes only the above-described components, a mobile terminal of a simple structure can be provided.
According to a further aspect of the present invention, the center station of the first aspect includes a unit for providing connection with the small zone communication system, a unit for requesting the identification number of a repeater with which the mobile terminal is communicating, a unit for receiving an identification number and detecting the position of the mobile terminal according to the received identification number, a unit for displaying a map in the proximity of the repeater, and a unit for displaying the position of the mobile terminal with a predetermined mark on the map.
Since the center station receives an identification number of a repeater with which the mobile terminal is communicating so that the position of the mobile terminal can be detected according to that number and displayed on a map, a center apparatus of low cost and high accuracy used in a position detection system of a mobile terminal can be provided.
According to a still further aspect of the present invention, a position display system of a mobile terminal employing a small zone communication system includes a repeater provided in each of a plurality of small zones, and a mobile terminal for carrying out communication with a repeater. The repeater provides its own ID information to a mobile terminal during communication with that mobile terminal. The position display system of the mobile terminal further includes a center station that can communicate with a mobile terminal. The center station detects the position of the mobile terminal according to the repeater identify information. Since a mobile terminal obtains a repeater identify information during communication with that repeater which is used to detect the position of the mobile terminal, the center station can easily identify where the mobile terminal is located in the plurality of small zones without using the information of the center control station.
Preferably, the mobile terminal includes a monitor for monitoring the intensity of an electric field of the plurality of repeaters, and a transmitter for sending the electric field intensity of the plurality of repeaters monitored by the monitor to the center station. The position detector has pattern information of a wave propagation according to the position of the mobile terminal. The position detector identifies the position of the mobile terminal according to the wave propagation pattern information and the electric field intensity from the plurality of repeaters.
Since the position of a mobile terminal can be identified according to the electric field intensity of the plurality of repeaters and wave propagation pattern information according to the position of the mobile terminal, the position of the mobile terminal can be identified at high accuracy.
According to yet a further aspect of the present invention, a position determination system includes a unit for obtaining the maximum propagation distance centered about a wave generation source for each level of electric field intensity to produce a first wave propagation pattern according to the obtained maximum propagation distance, a unit for detecting the arrangement and profile of a building around the wave generation source according to an electronic map, a unit for obtaining a crossing point of the first wave propagation pattern and the profile of a building, and a unit for automatically producing a second wave propagation pattern taking into account influence of the building from the crossing point of the first wave propagation pattern and the profile of the building.
Since the second wave propagation pattern is automatically produced taking into consideration the profile of a building from the crossing point between the first wave propagation pattern generated according to the wave maximum propagation distance centered about the wave generation source obtained for each electric field intensity and the profile of the building around the wave generation source obtained according to an electronic map, it is not necessary to take the trouble of determining a wave propagation pattern and computing according to the determined pattern. Therefore, a wave propagation pattern can be determined easily.
Preferably, there are a plurality of wave generation sources. A plurality of second wave propagation patterns are generated from the first wave propagation pattern on the basis of the plurality of wave generation sources and the profile of a building. A position is determined by detecting the overlapping portion of the plurality of formed polygons.
Since the overlapping portion of a plurality of second wave propagation patterns is obtained to determine the position using the overlapping portion, a position determining system that can easily determine a position can be provided.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.